Thin cathode ray tube with array of planar vertical deflection elements



OEHKUH lQUU Bi 3 1 3*"4229 OR 3 9 435 9 269 SR v A March 25, 1969 L. A.SHANAFELT ET AL 3,435,269

THIN CATHODE RAY TUBE WITH ARRAY OF PLANAR VERTICAL DEFLECTION ELEMENTSFiled Oct. 23, 1965 Sheet or 5 INVENTOR. LEO A. SHANAFELT ABRAHAM BANKSQQ Mew ATTORNEY March 25, 1969 SHANAFELT ET AL 3,435,269

THIN CATHODE RAY TUBE WITH ARRAY OF PLANAB VERTICAL DEFLECTION ELEMENTSFiled Oct. 23, 1965 Sheet g of 3 III:

. INVENTOR. LEO A. SHANAFELT ABRAHAM BANKS v BY ATTO R NEY March 25,1969 1.. A. SHANAFELT ET AL 3,435,269

THIN CATHODE RAY TUBE WITH ARRAY OF PLANAR VERTICAL DEFLECTION ELEMENTSFiled on. 25, 1965 Sheet 3 of s INVENTOR. LEO A. SHANAFELT ABRAHAM BANlATTORNEY United States Patent 3,435,269 THIN CATHODE RAY TUBE WITH ARRAY0F PLANAR VERTICAL DEFLECTION ELEMENTS Leo A. Shanafelt, 5823 KeokukAve., Woodland Hills, Calif. 91364, and Abraham Banks, 18710 Paseo NuevoDrive, Tarzana, Calif. 91356 Filed Oct. 23, 1965, Ser. No. 503,264 Int.Cl. H015 29/74 US. Cl. 313-78 4 Claims This invention relates generallyto a cathode ray tube of the type described generally in Patent2,795,731, issued June 11, 1957, to William Ross Aiken. Moreparticularly this invention relates to a novel modification of theembodiment of FIGURES 24 and 25 of said patent.

The cathode ray tube to which this invention relates is adapted to berelatively thin so that it may be utilized in a television set which,for example, hangs on the wall and protrudes from the wall no more than2 inches or the like or in a different version may be incorporated in ahand carried transistorized pocket television set, or may be provided asa means of displaying data for aircraft pilots in the relativelyconfined space of cockpits where space is at a premium.

Other advantages of this general type of tube are set forth in theaforementioned patent and in many subsequently issued patents relatingto the general type.

In the particular type of tube to which this invention relates, anelectron gun is provided at one side of a target screen to provide abeam of electrons with the axis of the gun lying in a planesubstantially parallel to that of the target screen. The gun is providedwith electrostatic or magnetic deflection means to cause the beam tosweep through an included angle of suitable size in a plane adjacent tothe target screen; the plane is substantially parallel to the targetscreen. A plurality of defiection elements are provided lying in a planewhich is parallel to the plane of the target screen and the plane whichthe beam sweeps, the plane which is being sweeped being between theplane of the deflection elements and the plane of the target screen. Thedeflection elements consist of electrically conductive material and maybe plates but are preferably transparent electrically conductivematerial coated on a suitable supporting surface which may be a glassplate and may be part of the envelope of the tube. Suitable voltages areapplied to the deflection plates in such manner that the voltage appliedto each is lowered successively for each vertical sweep of the raster.

The horizontal lines in the raster which is produced by such a tube arenot straight but are curved so that the entire raster has the shape of asegment of an annulus rather than having the shape of a rectangle. Theexistance of this type of difliculty is indicated in the aforementionedpatent in connection with the discussion of FIGURES 24 and 25 and isalso indicated in other subsequently issued patents. It has beensuggested that the difficulty may be overcome by providing suitablevoltage corrections by including suitable circuitry modifications in thesources for the horizontal and vertical sweep signals.

It has not been found possible to make suitably satisfactory correctionsin this manner which provide straight horizontal lines in the raster andthus it has not been feasible in this manner to obtain a suitable image,especially a suitable television image.

We have provided a solution for the problem which provides perfectlystraight lines in the horizontal sweep and an excellent picture. Oursolution furthermore is accomplished without adding any additional cost,effort, labor or attention to the circuitry or the tube and without, infact, adding any additional element whatever to the circuitry or thetube.

"ice

The object of the invention which has thus been accomplished is toprovide for all lines in the horizontal sweep in the above describedtype of tube to be straight in a manner which adds substantially nothingto the cost, the complexity or the difliculty in making either thecircuitry for the tube or the tube itself.

Other objects will become apparent from the drawings. and from thefollowing detailed description in which it is intended to illustrate theapplicability of the invention without thereby limiting its scope toless than that of all equvalents which will be apparent to one skilledin the art. In the drawings like reference numerals refer to like partsand;

FIGURE 1 is a schematic perspective view of the principal elements of atube according to the invention;

FIGURE 2 is a plan view of an array of vertical deflection elements in atube according to the invention;

FIGURE 3 is a plan view of another array of vertical deflection elementsin another tube according to the invention which is neither amodification nor a different embodiment from that of FIGURE 2 but merelya tube which differs in location of elements from that of FIGURE 2;

FIGURE 4 is a plan view of an array of vertical deflection elements inanother embodiment.

Referring now to FIGURE 1, there is shown a front envelope member 10which may be of glass and which may have target 11 coated thereon.Target or target screen 11 may be of any suitable fluorescent materialwhich may suitably be used for cathode ray tubes such as for televisionscreens or the like. Electron gun 12 is disposed at one side of screen11 with its axis lying in a plane substantially parallel to the plane inwhich screen 11 lies and by means of suitable electrostatic or magneticdeflection means well known in the art and not shown for simplicity, isarranged to provide an electron beam 13 scanning or sweeping in a planedefined by beam 13 and beam 13'. Deflection elements 14, respectivelydesignated A, B, C, D, and E, lie in a plane which is parallel to theplane of screen 11 and parallel to the plane defined by beams 13 and 13'and is spaced apart from these other two planes so that the planedefined by beams 13 and 13 lies substantially between the plane oftarget 11 and the plane in which elements 14 lie. Elements 14 areconductive members and may be metal plates attached to a suitableinsulating backing but each preferably consists of a coating oftransparent conductive material coated on to a supporting glass plate.For simplicity, the showing of such a glass plate or such insulatingmaterial has been omitted.

In any suitable manner shown in the prior art, electric generating meansmay be provided to provide each of elements 14 with a voltage whichvaries with time so that the voltage for each element is loweredsequentially to cause deflection of beams such as 13 or 13' toward andinto contact with screen 11 at a point which varies with time in avertical direction. Because several different means are shown in theaforementioned patent for controlling the voltage supplied to such anarray of vertical deflection plates, and because other means forsupplying such voltages are shown in other disclosures in the prior art,the description of such means is omitted here for simplicity. Apreferred means, however, is that shown in a copending application inwhich a plurality of neon tubes are fired sequentially to illuminatesequentially a series of photocells, the output of each of thephotocells being fed respectively to elements 14.

It will be noted that each of elements 14 is planar and that the topedge of each is straight, whereas, the bottom edge of each is curvedupwardly from the center to each side. Alternatively, the top edge ofeach may suitably be curved downwardly from the center to each side andthe bottom edge may be curved as described or may be straight ifdesired, or may be curved downwardly from the center to each side.

Referring now to FIGURE 2, there is shown the manner in which oneembodiment is provided. Referring, for example, to element E of elements14', the curve of the bottom of the element is so calculated thatdistance E over which beam 13A travels is equal to distance E" overwhich beam 13B travels and is also equal to distance 15'' over whichbeam 13C travels; the same is true for each of the other elements. Thusthe top edge of element C is straight, and the bottom edge of element Cis calculated to curve upwardly from the center towards each outside endin such fashion that portion C of beam 13A which passes over element Cis equal in length to portion C of beam 138 which passes over element C,and is equal to portion C' of beam 13C which passes over element C. Theamount of curvature may be slightly varied empirically if desired tocorrect for minor field variations and the like in order to providestraight horizontal lines in the raster.

Likewise, as shown in FIGURE 3, the position of the gun 22 with respectto the deflection elements 21 may be changed so that the average lengthof the beam 23 projected by the gun is changed, the number and relativespacing of the elements may be changed and the included angle 20 throughwhich the beam sweeps is changed. Just as described in connection withFIGURE 2, the distance through which the beam passes over each elementmay be the same for all portions of each element throughout the sweep ofthe beam.

Referring now to FIGURE 4, there is shown an embodiment in which each ofvertical deflection elements 24, respectively designated 24a, 24b, 24c,24d and 24a is provided with both a bottom edge and a top edge whichcurves upwardly from the center to each side. The curvature of each ofthese edges may be calculated by determining the radius of the arcthrough which the beam 26 (emitted by gun 27) sweeps at substantiallythe location of the edge. The downward curvature of the edge then ismade equal to the upward curvature of an are defined by a radiusextended from point 25 at which the beam is bent in or near the gun.Thus for the upper edge of element 2412, the radius of its downwardlyextending arc R is made equal to the radius of the arc R through whichbeam 26 sweeps at substantially the same point.

In general, the deflection elements are so provided, in accordance withthe invention, that the electrostatic field between the deflection arrayand the target screen is 4 altered with a correction equal and oppositeto the field or force which provides arcuateness to the line provided bythe beam.

It may thus be seen that the invention is broad in scope and includessuch modifications as will be apparent to those skilled in the art andis to be limited only by the claims.

Having thus described our invention, we claim:

We claim:

1. In a cathode ray tube having an envelope, a target screen in saidenvelope and an array of planar vertical deflection elements disposedsubstantially adjacent to a surface spaced from and opposite to saidtarget screen to control vertical sweep of an electron beam in theprovision of a raster on said target screen, an electron gun in asymmetrical position with respect to the ends of said verticaldeflection elements, below said elements, for injecting an electron beambetween said elements and said target screen, means for scanning saidbeam in a fan-shaped pattern between said array and said target screen,said pattern being in a plane if voltages on said elements and saidscreen are equal, each of said vertical deflection elements having anupper and lower edge and having at least one of said edges curved foraltering the electrostatic field between said vertical deflection arrayand said target screen to straighten the horizontal lines of saidraster.

2. The tube of claim 1, wherein the top edge of each of said deflectionelements is curved upwardly from the center to each side.

3. The tube of claim 2, wherein the bottom edge of each of saiddeflection elements is also curved upwardly from the center to eachside.

4. The tube of claim 3, wherein the curves of said edges have radiisubstantially equal to the radial distance of said edge from the pointnear the gun at which the beam bends.

References Cited UNITED STATES PATENTS 2,879,443 3/1959 Aiken 313-77 X2,885,595 5/1959 Gabor 31378 X 2,997,621 8/1961 Schlesinger 313-923,171,056 2/1965 Gabor 31378 X ROBERT SEGAL, Primary Examiner.

U.S. Cl. X.R. 31377

1. IN A CATHODE RAY TUBE HAVING AN ENVELOPE, A TARGET SCREEN IN SAIDENVELOPE AND AN ARRAY OF PLANAR VERTICAL DEFLECTION ELEMENTS DISPOSEDSUBSTANTIALLY ADJACENT TO A SURFACE SPACED FROM AND OPPOSITE TO SAIDTARGET SCREEN TO CONTROL VERTICAL SWEEP OF AN ELECTRON BEAM IN THEPROVISION OF A RASTER ON SAID TARGET SCREEN, AN ELECTRON GUN IN ASYMMETRICAL POSITION WITH RESPECT TO THE ENDS OF SAID VERTICALDEFLECTION ELEMENTS, BELOW SAID ELEMENTS, FOR INJECTING AN ELECTRON BEAMBETWEEN SAID ELEMENTS AND SAID TARGET SCREEN, MEANS FOR SCANNING SAIDBEAM IN A FAN-SHAPED PATTERN BETWEEN SAID ARRAY AND SAID TARGET SCREEN,SAID PATTERN BEING IN A PLANE IF VOLTAGES ON SAID ELEMENTS AND SAIDSCREEN ARE EQUAL, EACH OF SAID VERTICAL DEFLECTION ELEMENTS HAVING ANUPPER AND LOWER EDGE AND HAVING AT LEAST ONE OF SAID EDGES CURVED FORALTERING THE ELECTROSTATIC FIELD BETWEEN SAID VERTICAL DEFLECTION ARRAYAND SAID TARGET SCREEN TO STRAIGHTEN THE HORIZONTAL LINES OF SAIDRASTER.